Research On Preparation Technology Of High Sensitivity Hydrogen Detection Sensor Based On Nano Fibers

For extreme applications such as hydrogen detection in space,flammable gas detection in weapons production,and flammable ice detection in the deep sea,the development of hydrogen sensors for low-concentration hydrogen detection has important research significance.In order to further improve the sensor’s output response and improve the detection characteristics of the lower limit of hydrogen concentration,this paper introduces materials such as nanofibers and Pd nanoparticles.Based on the characteristics of large specific surface area,electrospinning technology and magnetron sputtering technology are used.The design,preparation technology and related performance testing of nanofiber high sensitivity hydrogen detection sensor were carried out.The main research results are as follows:Firstly,high-purity polyacrylonitrile nanofibers,5% graphene-doped and 10% graphene-doped nanofibers were prepared by electrospin method.According to the SEM micro-domain characterization,the diameter of the high-purity polyacrylonitrile nanofibers is maintained at 150 nm-300 nm.The thickness of the fibers is uniform and the fibers are randomly oriented.The fibers are intertwined and stacked together,from top to bottom;The diameter of the polyacrylonitrile nanofibers doped with 5% graphene is maintained at about 100 nm to 200 nm.Compared with the fiber material without graphene,the diameter is slightly reduced and the fiber distribution is more denser.Under low magnification magnification imaging,the surface of the fiber randomly appears as nanosheet-like structure;And the diameter of the polyacrylonitrile nanofiber doped with 10% graphene is maintained at about 50 nm to 100 nm.The fiber has the thinnest diameter compared to the first two materials.Conical spheres appear frequently throughout the imaged area and are randomly scattered at various locations in the SEM image.Secondly,Pd nanoparticles were deposited on the surface of the prepared nanofibers by DC magnetron sputtering.Pd nanoparticles were deposited on the surface of nanofibers and this can be demonstrated by EDX scanning analysis.And by SEM micro-area photo characterization and XRD scanning analysis,when the sputtering power is 180 w and the sputtering time is 45 s,the nano-Pd particles deposited on the nano-fibers are dispersed,and observed by observation,the grain size is about 22 nm.Thirdly,a high sensitivity hydrogen detection sensor based on organic nanofibers decorated by Pd nanoparticles was designed and fabricated.The substrate material is polyacrylonitrile nanofibers material and the nano Pd particles are hydrogen sensitive elements.The outer dimensions of the high sensitive low concentration hydrogen detection sensor are 2 cm×1 cm,and the distance between the two silver pastes as electrodes is 10 mm.Finally,the performance of the hydrogen sensor was tested and analyzed by the hydrogen sensor calibration system.The test used a 99.999% high-purity nitrogen gas and a 50 ppm nitrogen-hydrogen gas mixture.The resistance was measured by the four-wire method and the current was measured at 1 mA.The data acquisition time of the digital power meter is 1s,and the data can be automatically saved after the test is stopped.The performance test results of the hydrogen sensor based on high-purity polyacrylonitrile nanofiber material developed in this paper show that the maximum output response increases with temperature,and the two relationships are linearly related.At the same time,the maximum output response of the sensor is linearly related to the square root of the tested hydrogen concentration.The hydrogen sensor exhibits a high sensitivity to low concentrations of hydrogen.In particular,when the hydrogen concentration is 5 ppm,the maximum output response of the device is 6.55%.And after four cycles of testing,the hydrogen sensor’s maximum output response to 25 ppm hydrogen can still reach 10.63%.And the effects of graphene doping and nano-Pd particle sputtering power on the performance of the prepared high sensitivity sensor based on organic nanofibers decorated by Pd nanoparticles are discussed.The test results show that the maximum output response of the sensor increases with the increase of doped graphene concentration.What’s more,when the response speed increases,the maximum out response also increases.As to the influences of Pd nanoparticles sputtering power,it is observed that when the sputtering power of Pd nanoparticles is 90 W,the maximum output response of hydrogen detector to 25 ppm hydrogen is higher,and as the doping concentration of graphene increases,the response speed increases fast.When the sputtering time is the same,the performance of the sensor with DC source magnetron sputtering power of 90 w is better than that the sputtering power of 180 w.